Judge Wade Birdwell wrote in his ruling that the state did not have enough evidence to prove that Mason knew she was ineligible to vote when she cast a ballot in the 2016 election.
In a statement, the ACLU of Texas said this acquittal amounts to a "victory for Mason, a Black grandmother from Fort Worth, whose life was upended by the state's aggressive charges."
"I am overjoyed to see my faith rewarded today," Mason said in a statement. "I was thrown into this fight for voting rights and will keep swinging to ensure no one else has to face what I've endured for over six years, a political ploy where minority voting rights are under attack."